Electric scroll saw



June 11, 1935. E, MEYER ELECTRIC SCROLL SAW Filed March 16, 1934Patented June 11, 1935 UNITED STATES PATENT OFFICE ELECTRIC SCROLL SAWEdwin L. Meyer, Bridgeport, llonn.

Application lllarch 16, 1934,, Serial No. 715,835

16 Claims, ((31. 219 -29) and in way out out designs and do other wousually done with a scroll saw.

"-on of a device of this kind having a pistol 3:: so disposed that longlegs of the U-shaped frame are held vertically so that the motions ofthe cutting Wire may. be in a substantially horizontal plane while thework is held vertically. 'Wi'i tools of this kind as heretoforeprovided, the worlr was held horizontally and the cutting element wasmoved vertically. It has been found that by having the cutting elementdisposed as alcove stated, the cutting element may be con trolled andthe work may be done with greater ease and accuracy. While beingreciprocated horizontally, the tool may be moved vertically or laterallyas the work progresses without tiltingor swinging the frame, for theincandescent wire is operative on all sides.

Another feature of this invention is the provision of a switch on thehandle for opening and closing the circuit including the resistancewire. By manipulating the switch, the wire may be made incandescent onlywhen this is actually re quired. The finger-piece for the switch is inthe shape of a trigger and is carried by the handle or grip in theposition usually occupied by a trigger in a pistol.

Another feature of this invention is the rovision of means forcontrolling the operative length of the wire. Should it be found thatbecause of the thickness or characteristic of the wood worked upon thewire cools too rapidly upon contact with the wood, this resistance wirein effect may be shortened so as to increase its resistance and raiseits temperature. This is of gi'eat practical importance, since, by asimple adjustment, the desired working temperature of the wire can beobtained. 7

A further feature of the present invention is.

applied to wood, bowing of the wire is permitted with the result that aflat-bottom out is not produced. According to the present invention, theframe is made relatively rigid and one end or the wire is yieldinglymounted, y; x mounting for that end of the wire operates ciently onlywhen pulled in a direction p to the wire, when a lateral pi'essr-"e s applied thereto, as ls ively no tar to the present invention, the light ison so long as the tool is connected to a source of current and is notaffected by the operation of the switch controlling the passage ofcurrent to the cutting wire.

One of the more important features .of the present invention is theemployment of supply current of very low potential and high current, andthe heating wire employed is suited to these conditions. The currentsupply is preferably obtained from a transformer connected toalternating house current. By employing current having a potential of afraction of a volt which has been found satisfactory, there isavoidedthe danger of the user being shocked or injured by short-circuiting theterminals with part of his body when applying or adjusting the wire, orby casual contact in the use of the device.

Other features and advantages will hereinafter appear.

In the accompanying drawing Figure 1 is a side elevation of the electricsaw of the present invention.

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1, and showingthe means for securing the end of thewire remote from the handle.

Fig. 3 is a detail view, partly in section, taken on the line 3-4 ofFig. 1. v 5

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 1. i

Fig. 5 is a vertical sectional view, taken on the line 5-5 of Fig. 1.

Fig. 6 is a transverse section through the handle, taken on the line 6-6of Fig. 1.

Fig. 7 is a sectional view showing the means for securing the end of thewire adjacent the handle.

means for supplying current to $7,: tool.

" may make the'wire 3| incandescentor not at a relatively large U-shapedframe I having an upper horizontal leg H and vertical legs l2. One otthelegs I! is made somewhat shorter than the other, and has its end fittingin a socket l3 in a handle I4 having a pistol grip IS. Thepistol gripincludes a central metal portion l5 and side portion ll of wood. Betweenthese there is provided a chamber or opening l8 through which passcurrent supply wires I3. These wires enter the handle through a bushedopening 20 at the bottom of the pistol grip. 7

At the lower end of the longer leg i2 of the frame there is secured aT-shaped bearing member 2| having a square hole 22 in which there isslidably mounted a square rod or slide 23. One end of this rod carries anut 24 against the head of which bears a spring 25 tending to move theslide in the direction of the arrow shown in Fig. l. The other end ofthe slide carries a flange 26 limiting the movement of the slide in thedirection of the arrow shown in Fig. 1. Beyond the flange 26, the slidehas a fiat portion or shelf 2,1 on which is carried a clamp 28 having ascrew 29 hearing on one side of the shelf H and a saddle 30 located atthe opposite side of the shelf.

This clamp or binding post is intended to secure to the slide 23 a highresistance Wire 3! which is the cutting element of the presentinvention. When the wire is slid between the shelf 21! and saddle 3d andthe screw 28 rotated, the saddle is drawn up to securely clamp the wireto the shelf. The shelf may have a V-shaped notch 32 as shown in Fig. 2,to locate the wire centrally of the rod.

The opposite end of the wire 3| *is secured in place by a similar clamp28(but in this case the is formed on a stud 33 having a head 34 engagingthe inner end of a bushing 35 mounted in a screw-threaded portion 36 inthe metal mem-= her Is of the handle. Thebushing 35 is made ofinsulating material and is applied to the stud,

before the clamp 28 is mounted on the shelf 27!, and serves to insulatethe stud, clamp and the near end of the wire 3| from the handle.

The remote end of the wire 3| is connected to the sourceof currentthrough the slide 23, bearingv 2|, frame I0, and metal member I6 of thehandle by means of 'a binding screw 31 carried by the portion I 3 andconnected to one wire 38 of the cable supplying the device with current.The other or near end of the wire 3| is connected to a source of currentwhen desired by a switch blade 39 connected to a binding post 40 carriedby and insulated from the handle and connected vto the other wire 4| orthe cable supplying curthere is provided a trigger 42 pivoted at 43 andhaving an arm 44 engaging the switch blade and in position to move theswitch blade into contact with the head 34. The trigger 42 is placed onthe handle l5 in the position corresponding to the trigger of a pistol,and hence, by merely pressing on and releasing the trigger", the userwill. I

When the wire 3| becomes heated and incandescent, it naturallyincreasesin length or elongates. This would cause it to sag unless provisionswere made to avoid it. According to the present invention, this is doneby securing the remote end of the wire 3| on the slide 23 in such a waythat the spring 25 tends to move the slide in the direction of thearrow, thereby keeping the wire under tension and taut. When, however,the wire is applied with some force to the work, it is undesirable thatthe wire bow substan t'ally, and accordingly at this time the slideshould not move easily. By making the slide square, the tendency for theslide to move when the wire is applied to the work is avoided, thelateral pressure on the slide causing the flat side of the slide toengage the fiat surface of the hole 22 and bind in whatever position itmay at that time be.

By providing these means for holding and con trolling the remote end ofthe resistance wire, the U-shaped frame It may be made substantiallyrigid so that it may impart true and intended motion to the resistancewire in tracing a design.

In order to facilitate the tracing of the design with the resistancewire 3|, the saw, according to the present invention, is provided with alamp 45 mounted in a socket 46 in the metal part I6 of the handle andextending into the chamber IS. The center contact of the lamp is engagedby an upper extension 47 on the switch blade 39. It will thus be seenthat the lamp 45 will glow continuously even though the switch blade 39is disengaged from the head 34 of. the wire holding upright. The trigger42 is then operated to'close I the circuit and causing the wire 3| tobecome incandescent, or at least hot enough to cut the wood. When thewire is so conditioned, it is drawn back and forth over the woodfollowing the outline of the design to' be cut. The back and forthmotion of the wire is necessary, since, according to the presentinvention, the cross section and heat of the wire is such that ifallowed to remain in one position, the portion in contact with the ,woodwould cool so rapidly as not to burn. By moving the wire back and forth,a hot portion of the wire is constantly beng applied to the wood,and theportion just leaving the wood has an opportunity to become reheated.

In practice, it is sometimes desired to have the wire 3| hotter thanother'times. For this purpose, the wire-3| is made longer than thenormal distance between the clamp 28, and a portion of the end of thewire 3| 0. is allowed to project beyond the clamp in the passage 23a inthe slide 23. If it is desired to make the wire hotter than normal, thescrew on the slide 23 is loosened and the slide is pulledout fartherthan normal, thus shortening the; wire electricallinthe surplus end 3laprojecting-further into theopening 23a. If a cooler wire is desired,rever'seoperations are performed.

' As diagrammatically illustrated in Fig. 8, the

wires 38 and 4| are connected to a secondary Winding 41 on a transformer48 having a primary winding 49 connected to} the commercial power line50.

The ratio of the windings 41 and 49 1 is such that an electromotiveforce ofisomewhat less than one volt and proportionatelyhigh cub rent isimpressed on the circuit including the wires 38 and 4| and the heatingwire 3]. Cur-v rents ofsuch valuei arenot harmful, and accord aooassoingly the saw may be handled anywhere desired, or may be contacted withcasually without shock 'imury, except, of course, by contacting directlyti e incandescent wire it which would produce a In i there is shown amodified form of clamp for holding the remote end of the resistance wirell. pair of jaws El pivoted on the reduced end 52 of longer leg ll ofthe frame and having opposite the pivot 52 arms 55 across which there isconnected a spring 56 tending to pull the arms andv jaws 5i together sothat the latter may tightly grip the end of the resistance wire 3|. Torelease the jaws, a pair of toggle-links 55 are connected to the ends ofthe arms 53, and at the pivot point of the toggle-links there isprovided a fdngenpiece Ell.

Upon applying pressure to the finger-piece 51, the toggle-links 55 movetoward straightened or parallel positions, and, in doing so, spread thearms 53 jaws iii to permit the removal or insertion of the end of theresistance wire 3! between them. Upon release of the finger-piece 51,the spring draws the jaws 5! together. By having the actuating devicefor the jaws in the form of the toggle, the jaws may be easily opened inspite of the fact that the spring 54 is very strong.

The form of the invention shown in Fig. 9 is particularly advantageouswhen the work to be done requires that the wire at be passed through aperforation or drilled hole in the work, for in this case the wire 3!may be threaded through the hole and easily and quickly clamped in theremote or opposite end of the frame, the near end of the wire beingattached to the binding post on the handle.

Variations and modifications may be made within the scope of thisinvention and portions of the improvements may be used without others.

Having thus described the invention, what is claimed as new and forwhich it is desired to obtain Letters Patent, is:-- r

An electric scroll saw comprising a rigid U- shaped frame; a resistancewire; and binding posts on opposite legs of the frame having thumbscrews for clamping the resistance wire and holdthe wireacrcss the openend of the frame, one of binding posts being yieldlngly and mounted onthe leg of the frame carrying it holding the resistance wire taut as itd contracts incidental to the heating of the wire.

An electric scroll saw comprising a rigid U- frame; a resistance wire;and binding posts on opposite legs of the frame having thumb screws forclamping the resistance wire and holding the wire across the open end ofthe frame, one of said binding posts being yieldingly mounted on the legof the frame carrying it and holding the resistance wire taut as itexpands and contracts incidental to the heating and cooling of the wire,said binding post being mounted on a slide and said slide having abearing on the leg of the frame on which it is carried, and a springnormally tending to move the slide and applying a stretching action tothe wire to maintain it taut.

3. An electric scroll saw comprising a rigid U- shaped frame; aresistance wire; and binding posts on opposite legs of the frame havingthumb screws for clamping the resistance wire and holding the wireacross the open end of the frame, one of said binding posts beingyieldingly mounted on the leg of the frame carrying it and holding theresistance wire taut as it expands and con-- em: r

in this form, there is'provlded a tracts incidental to the heating andcooling of the wire, said binding post being mounted on a slide and saidslide having a hearing on the leg of the frame on which it is carried,and a spring normally tending to move the slide and applying astretching action to the wire to maintain taut, said slide and bearingtherefor being square in cross-section whereby the slide tends to jam inthe bearing when pressure is applied laterally to the slide to preventexcessive bowing of the resistance wire when applied to the work.

4. An electric scroll saw comprising a rigid U- shaped frame; aresistance wire; and binding posts on opposite legs of the frame havingthumb screws for clamping the resistance wire and holding the wireacross the open end of the frame, one of said binding posts beingyieldingiy mounted on the leg of the frame carrying it and holding theresistance wire taut as it expands and contracts incidental to theheating and cooling of the wire, said binding post being mounted on aslide and said slide having a beaing on the leg of the .frame on whichit is carried, and a spring normally tending to move the slide andapplying a stretching action to the wire to maintain it taut, theengagement between the slide and its bearing being such as to tend tocause the slide to jam and remain held against longitudinal movementwhen lateral pressure is applied to the slide.

5. An electric scroll saw comprising a rigid U- shaped frame; aresistance wire; and binding posts on opposite legs of the frame forclamping the resistance wire across the open end of the Elli till

frame, one of said binding posts being yieldingly mounted on the leg ofthe frame carrying it and holding the resistance wire taut as it expandsand contracts incidental to the heatingand cool ing of the wire, saidbinding post being mounted on a slide and said slide having a bearing onthe leg of the frame on which it is carried, and-a spring normallytending to move the slide and applying a stretching action to, the wireto maintain it taut, said slide having a passage in line with the wireto receive the end of the wire when the slide is moved longitudinallywith relation to the wire to shorten the effective length of the wireand thereby cause the wire to be brought to a greater degree ofincandescence when energized.

6. An electric scroll saw comprising a suhstantially U-shaped frame; ahandle secured to one of the legs of the U'JSI'IELDB frame; a resistancewire stretched across the open side of the frame; a pair of bindingposts, one securing and electri caily connecting one end of theresistance wire to thefranie and the other securing the other end oftheresistance wire to the handle and insulated therefrom and from theframe; a current supply wire connected to the frame; a switch blade; atcurrent supply wire connected to the switch blade; and a finger piecefor moving the blade into engagement with the binding post which isinsulated from the handle and frame.

'7 An electric scroll saw comprising a substantially 'U-shaped frame; ahandle secured to one of the legs of the U-shaped frame; a resistancewire stretched across the open side of the frame; a pair of bindingposts, one securing and electrically connecting one end of theresistance wire .to the frame and the other securing the other bladeinto engagement with the binding post tially U-shaped frame; a handlesecured to one of the legs of the U-shaped frame; a resistance wirestretched across the open side of the frame, said handle having achamber therein open at the bottom; current supply wires entering thechamber through said opening and terminating in said chamber, one ofsaid wires being connected to the frame and from the frame to due end ofthe resistance wire; a. switch in said chamber for connecting the otherwire to the other end of the resistance wire; and a lamp carried by thehandle connected to said ungrounded current supply wire independently ofsaid switch.

9. In a device of the character described, an

electric resistance wire forming a burner element;

a frame in which said wire is carried and having an open side acrosswhichxthe said wire is stretch= ed, said frame having a hand grip theaxis of which forms an angle of greater than 30 with the axis of thewire by means of which hand grip the frame is manipulated to draw theresistance 'wire over the work; means for supplying low voltage highamperage currents to said wire to heat the same, said means including atransformer supported independently of said frame and having a primaryconnected to a source of house current, a secondary, flexible wiresconmeeting the secondary withsaid resistance wire, and a switch carriedby the frame to open and close the circuit including, said secondary andsaid resistance wire; and a finger-piece for said switch carried by thehand grip to be operated by the finger of the operators hand holding thehand grip to instantly openand close the circuit leading to theresistance wire.

iii. In a device of the character described, an electric resistance wireforming a burner element; a frame in which said wire is carried and towhich one end of the wire is electrically connected, hav ing an openside across which the said wire is stretched and having a wire holderinsulator for the frame, saidframe having a hand grip by means of whichthe frame is manipulated to draw the resistance wire over the work;means for supplying low voltage high amperage currents to said wire toheat the same, saidmeans including a transformer having a primaryconnected to a wires connecting the secondary with said resistance wire,one of said wires being electrically con-- nected to the frame, and aswitch carried by the frame to open and close the circuit including saidsecondary, one of said flexible wires, said-resistance wire, the frame,and the other flexible wire at a point between the flexible wire andinsulated resistance wire holder; and a finger-piece for said switchcarried by the hand grip to be 'operated by the finger of the operatorshand holding the hand grip to instantly open and close the circuitleading to the resistance wire. I

11. In a device of the character described, an electric resistance wireforming a burner element; a frame in which said wire is carried andhaving an open side across which the said wire is stretched, said framehaving a hand grip the axis of which forms an angle of greater than 30with the axis of the wire, by means of which hand grip the frame ismanipulated to draw the resistance wire over the work; means forsupplying the frame;

low voltage high amperage currents to said wire to heat the same, saidmeans including a switch carried by the frame; and a finger-piece forsaid switch carried by the hand grip to be operated by the finger of theoperators hand holdingthe hand grip to instantly open and close acircuit supplying current to the resistance wire.

12. An electric/scroll sawcomprising a rigid U-shaped metal frame; aresistance wire adapted to be removably carried across the open side ofmanually releasable wire-gripping means on opposite legs of the frame;means for mounting one. of said wire-gripping means on one leg of theframe in position fixed against movement axially of the wire; means formounting the other wire-gripping means on the other leg of the frame forslidable movement relative to the frame and axially of thewire;resilient means normally tending to cause the slidably mountedwire-gripping means to move axially of the wire away from theotherwire-gripping means to hold the wire gripped thereby taut, said slidablymounted wire-gripping means being in electrical engagement with theframe; means for insulating the fixed wire-gripping means from theframe; and means for supplying currentto the resistance wire throughsaid frame.

13JAn electrical scroll saw comprising a U- shaped metal frame; aresistance wire adapted to be removably carried across the open side ofthe frame;; manually releasable wire-gripping means on opposite legs ofthe frame; means for mounting one of said wire-gripping means on one legof the frame in position fixed against movement axially of the wire;means for mount;- ing the otherwire-gripping means on the other leg ofthe frame for slidable movement relative to the frame and axially of thewire; resilient means normally tending to cause the slidably mountedwire-gripping means to move axially of the wire away from the otherwire-gripping means to hold the wire gripped thereby taut, said slidablymounted wire-grippingmeans be ing in electrical engagement with theframe; means for insulating the fixed wire-gripping l means from theframe; flexible wires for supplying current to said resistance wire, oneof said wires being in electrical engagement with the frame; andmanually "operable means for @188? trica'lly connecting the other wireto the fixed and insulated wire-gripping means.

14. An electric scroll saw comprising a U- shaped metal frame; aresistance wire adapted to be removably carried across the open side ofthe frame; manually releasable wire-gripping means on opposite legs ofthe frame; means for mounting one of said wire-gripping means on one legof the frame in position fixed against movement axially of the wire;means for mounting the other wire-gripping ineanson the other leg of theframe-for slidable movement axially of the wire; resilient meansnormally tending to cause the slidably mounted wire-gripping means tomove axially of the wire away from the other wire-gripping means to holdthe wiregripped thereby taut, said slidable wire-gripping, means beingin electrical engagement with the frame;

-means for insulating the fixed wire-gripping trical engagement with theframe; and manual- 1y operable means on the hand grip for electrithewire gripped thereby taut; and means for axially of the wire; means formounting the other wire-gripping means on the other leg of the frame forslidable movement relative to the frame and axially of the wire;resilient means normally tending tocause the slidably mountedwire-gripping means to move axially of the wire away from the otherwire-gripping means to hold 16. An electric scroll saw comprising a U-shaped frame; a. resistance wire adapted to be removably carried acrossthe open side "of the frame; manually releasable wire-gripping means onopposite legs of the frame; means for mounting one of said wire-grippingmeans on one leg of the frame in position fixed against movementaxialiyof the wire; means for mounting the other wire-gripping means onthe other leg of the frame for slidable movement relative to the frameand axially of the wire; resilient means normally tending to cause theslidably mounted wire-gripping means to move axially of the wire awayfrom the other wire-gripping means to hold the wire gripped therebytaut; and means for supplying current to said resistance wire, theslidable wire-gripping means having a pair of wire-gripping jawsnormally urged toward each other to grip the end or the wire, and meansconnected to the jaws including a finger-piece adapted to be moved in adirection toward the wire to open the jaws to receive' the wire and atthe same time to cause the wire-gripping means 'to slide toward the wireagainst the tension of it away from the

